1. Field of the Invention
The present invention relates to a correction circuit correcting a current pulse waveform applied to a surface-emitting semiconductor laser that emits laser light from a top thereof, and relates to a drive circuit and a light emitting device each having the correction circuit. In addition, the invention relates to a method of correcting the current pulse waveform applied to the semiconductor laser.
2. Description of Related Art
The surface-emitting semiconductor laser, which emits light in a direction perpendicular to a substrate unlike a Fabry-Perot cavity laser in the past, may have many resonator structures arranged in a two-dimensional array on the same substrate. Therefore, the surface-emitting semiconductor laser is recently noticed in various technical fields of data communication, printers and the like.
The surface-emitting semiconductor laser typically includes a mesa resonator structure formed by stacking a lower DBR layer, a lower spacer layer, an active layer, an upper spacer layer, a current narrowing layer, an upper DBR layer, and a contact layer in this order on a substrate. In such a semiconductor laser, an oscillation wavelength is determined by an effective resonator length of the resonator structure, and magnitude of light output is maximized at an emission wavelength corresponding to a band gap of the active layer. Therefore, the resonator structure and the active layer are typically configured such that the effective resonator length of the resonator structure is equal to the emission wavelength of the active layer (see Japanese Patent Application, Publication No. 2008-306118).